The present invention relates to a process and a facility for testing the tightness of the package for a packaged object.
Food stuffs, pharmaceuticals, objects used in the area of medicine like, for example, disposable items, etc. are generally contained in a package (foil, bottle or sealed ampoules, and alike). It is the purpose of this package to protect the packaged object against any contamination from the outside. In the case of food stuffs, the package frequently serves the additional purpose of avoiding a loss of flavour in the packaged goods. These and other objectives can only be fulfilled by the selected package if it provides a hermetically tight seal.
It is the task of the present invention to create a process and a facility through which the tightness of a package for a packaged object may be checked easily, quickly, and reliably.
In the process according to the present invention, it is required that a test gas be contained within the package. For example, this may be a protective gas for the packaged goods (for example, nitrogen, argon, carbon dioxide, or alike). An other possibility is to ensure, in the course of the packaging process, that a typical test gas, like helium, is introduced into the package. It is essential that a detector is in a position to discern between the test gas present in the package of the packaged object and air. It is particularly advantageous when the package contains a share of helium gas amounting to 5 to 25%, by volume and preferably 10% by volume.
The tightness of the package is inspected according to the present invention by introducing the packaged object into a test chamber formed by two extensible foils, so that the space between the foils in which the packaged object is contained, is evacuated in such a manner that the foils can wrap the packaged object. At least in the areas of their surfaces which face the packaged object and in which the tightness of the package is to be inspected, the foils are provided with a layer of material which form a coherent intermediate space over the areas of the package which are to be inspected. This intermediate space is evacuated down to a pressure lower than the pressure within the package. The evacuated intermediate space is connected to a detector sensitive to the test gas to determine if test gas escapes outwards through the inspected area of the package.
A special advantage offered by the process according to the present invention is, that the test chamber will always adapt itself to the shape of the test object, resulting in a minimum volume which may be rapidly evacuated. Moreover, a test chamber of this kind is of greater simplicity and lighter in weight compared to known leak testing chambers which, for reasons of their ability to resist pressures, need to be designed to be sufficiently stable. Finally, the areas of the foil resting against the package offer a means of protection for the package. Even highly sensitive packages may be exposed to a relatively high pressure difference, this pressure difference having a decisive influence on the sensitivity of the leak testing process.